Some of the most common and widespread of
all aquatic birds are the ducks. They breed on
all continents except Antarctica, and are noted
for their long-distance seasonal migrations along
well-established flyways. Many species such as
the mallard (Anas platyrhynchos) and northern
pintail (Anas acuta) are indicator species of wetlands,
waterways, and water courses, but others,
such as the Baikal teal (Anas formosa) and
Laysan duck (Anas laysanensis) are very limited in
numbers and distribution. Most waterfowl are
important food resources for native peoples, and
revenues from duck hunters promote local economies
and fund wildlife refuges.Wildlife enthusiasts
value the rich variety of ducks and the brilliant
colors of the males, called drakes, of many
species.

Physical Characteristics
Ducks are placed in the avian order Anseriformes
along with the screamers, swans, and geese. The
long-legged screamers lack webbed feet and are
placed in their own family, the Anhimidae. The
ducks, geese, and swans are gathered in the family
Anatidae and are collectively called waterfowl.
The anatids are united in having webbed feet, a
boat-shaped body, a dense covering of feathers,
and a broad and somewhat flattened bill that is
variously modified for straining minute surface
organisms, gathering shellfish, grazing on aquatic
plants, or catching fish.
Ducks differ from swans and geese in several
ways. They are generally smaller and have shorter
necks and legs, which are set well back on the
body. They are good swimmers but walk with a
peculiar waddling gait on land. Ducks are also
distinguished in having scutellate (overlapping)
scales on the front of their legs, while geese and
swans have netlike or reticulate scaling.
Unlike their larger kin, ducks have two molts
each year. The first molt occurs after breeding in
males and shortly later in females. During this
molt, ducks shed their flight feathers and males
trade their bright breeding plumage for the plain
plumage colors similar to those of females, called
an eclipse plumage or hiding plumage. The plain
colors of the eclipse plumage camouflages the
flightless birds until their new flight feathers
grow. The second molt occurs in late summer or
early fall and produces the bright breeding plumage
of males in preparation for courtship on their
wintering grounds.
Ecologically, all ducks are birds of aquatic habitats
that reach their greatest abundance in the innumerable
ponds, shallow lakes, and marshes of
the world. Several species are sea ducks that
frequent shore habitats, estuaries, and coastal
marshes during the nonbreeding season.

Courtship and Nesting
Courtship and pair formation occurs on wintering
grounds as males and females engage in speciesspecific
displays. Males of many species perform
intricate head and tail jerks that "point" to the
bright metallic colors of their wing speculum.
Many sea ducks add a courtship finale by flicking
water spurts with their head or feet, all the while
bowing and cooing. The stiff-tailed ducks of the
tribe Oxurinae twist their heads far over their
backs, then violently thump their bills against the
inflated necks, uttering a stream of bubbles and a
series of burps.
Following courtship the female builds a nest of
reeds, sedges, and grasses in marshes or along the
shallow, weed-choked margins of lakes and
ponds. The mergansers and wood ducks nest in
cavities in trees, while shelducks are unique in selecting
burrows in which to lay their eggs.
In most species, the female alone builds the
nest of nearby materials and lines it with downy
feathers plucked fromher breast. The down feathers
provide wonderful insulation for the eggs and
are arranged in layers over the eggs for protection
from predators when the female leaves the nest to
find food.
Most ducks lay relatively large clutches of
eight to twelve smooth, white eggs. A few species,
such as the black-headed duck (Heteronetta
atricapilla) of South America, are brood parasites
that lay their eggs in nests of other ducks, coots,
and ibis.
Incubation begins when the clutch is complete,
ensuring that all of the young hatch at the same
time. Incubation takes about a month (twentytwo
to forty-one days). The precocial young are
densely covered in a fluffy coat of down feathers.
In most species, the young abandon the nest
shortly after hatching to accompany the female,
who leads them to nearby feeding grounds. The
young instinctively feed themselves under the
watchful eye of the female, who marshals them to
safety in the weeds if danger threatens. Predation
often decimates the young of a nest, as snapping
turtles, fish, foxes, coyotes, hawks, and owls are
quick to snap up the defenseless young. Those
that survive fledge in about a month and may remain
in the company for several more weeks.
In some species, the young accompany the female
on the southward migration, but most
young migrate on their own, relying on inbuilt genetic
programming to fly hundreds and sometimes
thousands of miles using the sun or stars or
both as navigation aids. Many species memorize
landmarks such as lakes and river courses, which
supplement celestial navigation aids on future
migrations. Studies have also suggested that at
least some ducks are able to tap into the earth's
magnetic field for directional aid on overcast
days, when other cues are unavailable.

Duck Tribes: Anatini
The ducks are subdivided into several tribes on
the basis of anatomical and behavior differences.
Several tribes contain forms intermediate between
ducks and their near relatives, the geese.
The familiar puddle ducks of ponds and
marshes belong to the tribe Anatini. They are
called tippers or dabblers because of their habit of
tipping up to feed in shallow waters of ponds,
marshes, and rivers. The dabblers have feet set
farther forward on their bodies than other ducks
and bound into the air when taking flight. Males
of this group usually have a brightly colored, iri-
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descent wing patch or speculum and are often
brightly colored about the head and neck, while
females are drab colored.
There are about forty-one species of dabbling
ducks worldwide, of which ten breed in North
America. Some typical dabblers include the teal,
widgeons, pintails, gadwalls, and shovelers. The
best-known dabbler is the mallard, which occurs
in both wild and domesticated forms. Most of the
domestic species, such as the barnyard duck and
Indian duck, are probable descendants of the mallard.
Dabbling ducks are surface or shallow water
feeders of creeks, ponds, and marshes. Some
strain food from soft mud, others feed on the
water surface, and still other species tip up and
then stretch their necks down into the water, taking
food from submerged vegetation or feeding
on the vegetation itself. Food consists of the
leaves, roots, tubers, and seeds of floating or submerged
vegetation and a wide variety of small animals,
mostly shrimp, scuds, shellfish, and insects.
Long-necked dabblers like the northern
pintail (Anas acuter) tip up to feed directly on the
bottom. Smaller species such
as teals feed in shallower
waters or on mudflats. The
broad, spatulate bill of the
northern shoveler (Anas clypeata)
strains minute organisms
fromthe water surface.
Dabblers are found on all
continents, but they are especially
plentiful along interior
ponds, marshes, and
creeks. In most dabblers, the
male is jealously attentive to
the female during courtship
but deserts her shortly after
the eggs are laid, leaving her
to defend the nest and raise
the young entirely on her
own. She builds a crude nest
of grasses and weeds lined
with down from her breast.
After abandoning the female,
the male may seek another
female to repeat the performance. If none is
available, they spend the rest of the breeding season
loafing and hiding while in the eclipse plumage.
After their second molt, the males sport
bright new feathers to enter the winter months,
during which courtship and pair formation for the
following breeding season takes place.

Aythyinae, Mergini, Cairini, and Oxyurinii
The pochards (redheads), canvasback (Aythya
valisineria), and scaups belong to the tribe
Aythyinae, which are called sea ducks or bay
ducks. They frequent coastal locations in winter
but build a floating nest among the reeds and
grasses of interior lakes, rivers and marshes. Most
diving ducks have short tails and wings, but large
paddle feet with a distinctive, paddlelike flap on
the hind toe for diving. They feed mostly on underwater
plants and animals. If danger threatens,
diving ducks submerge and can swim underwater
for long distances. They take flight by skittering
along the top of the water. Because they have
short wings on large bodies, most bay ducks fly
390 вЂў Ducks
The mallard duck is a common sight on the ponds and lakes of North America.
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with rapid wing beats and always appear in a
hurry in flight.
The tribe Mergini includes a varied mix of
mergansers, scoters, eiders, goldeneyes, and the
spectacularly colored harlequin (Histrionicus
histrionicus) and oldsquaw (Clangula hyemalis).
Mergansers are powerful divers that pursue fish
underwater, catching and holding them with their
narrow, serrated bill. They nest in cavities in trees
or in rock crevices along rivers and streams, as do
the goldeneyes of this tribe. The tribe also includes
eiders, which nest in the circumpolar Arctic tundra.
Eiders are the source of eiderdown, which the
female plucks from her breast to line the nest and
insulate the eggs and young. The most striking of
the Mergini is the harlequin
duck, with its patchwork quilt of
chestnut, blue, and white plumage.
Harlequins feed in cold,
fast-flowing Arctic streams.
Members of the tribe Cairini
have long legs and sharp claws
which enable them to clamber
about branches and limbs. Called
wood ducks or tree ducks, they
include the gorgeously colored
wood duck (Aix sponsa) of North
America and mandarin duck
(Aix galericulata) of southeast
Asia. This tribe also includes
the drab muscovy (Cairina moschata),
which occurs widely in
both wild and domesticated
forms. Unlike other tribes, the
wood ducks frequent the gallery
forests of rivers and lakes, forested
swamps, and woodland
pools. They typically nest in tree
cavities just adjacent to water.
When old enough, the downy
young half tumble and half
jump into the water below the
nest cavity.
The ruddy duck (Oxyura jamaicensis)
exemplifies the tribe
of stifftails called Oxyurinii. These
dumpy little ducks are predominantly reddish or
brownish in color and have upright tails for which
they are named. Except for teals, the stifftails are
small ducks that are noted for laying exceptionally
large eggs for their body size. For example,
the female ruddy duck, although scarcely weighing
a pound herself, lays a clutch of fourteen eggs,
weighing a total of nearly three pounds, with each
egg averaging over 2.5 by 1.75 inches in length
and width.

Dendrocygnini, Merganettini, and Tadorini
The long-legged members of the tribe Dendrocygnini
are whistling ducks. Considered by some
to be more closely related to geese than to ducks,
they are named for the sound of their wings during
flight and for their characteristic whistle when
taking off. Like the wood ducks to which they
are sometimes allied, whistling ducks frequent
forested swamps and rivers where they feed by
straining organisms from the water surface.
The smallest and perhaps the most unusual
tribe of ducks is the Merganettini, which consists
of a single species, the torrent duck. This longlegged
duck seems to be the Latin American
equivalent of the harlequin, as it makes its home
in swift-flowing streams of the high Andes.
Several intermediate forms of waterfowl also
take the name duck. The shelduck and sheldgeese
of the tribe Tadorini are coastal forms that resemble
geese but are probably related to the dabbling
ducks. Mostly Old World in distribution, the
males have the bright wing patch characteristic of
the dabblers. They are larger ducks with heavy
bills for pulling up rotting roots and tubers or extracting
molluscs frombottom mud. The tribe also
includes the steamer ducks of South America and
the Falkland Islands. Although powerful swimmers
and divers, two of the three steamer species
are flightless. They typically wade in shallows or
walk on water lilies and other aquatic plants as
they feed on a variety of organisms. The magpie
goose (Anseranas semipalmata) of Australia (tribe
Anseranatini) is a gooselike duck with a long hind
toe and slightly webbed feet. It differs from ducks
in having a gradual molt so that a flightless period
does not occur. Like geese, the magpie goose
spends much time on land foraging for grains and
other vegetation matter.

Food, Hunting, and Recreational
Opportunities Offered by Waterfowl
All ducks are of interest to wildlife enthusiasts
and birders because of their spectacular massed
migrations, colorful males, and often intricate behaviors.
For centuries, native peoples on all continents
have found many species to be an important
seasonal food source, eating the meat of adults
and young and harvesting eggs. Eiderdown is famous
for its heat-retaining qualities and has been
used by generations of northern peoples for stuffing
pillows, mattresses, quilts, and outerwear.
The ever-increasing impact of hunting resulted
in a decline of many of the more desirable species
which led, in turn, to the establishment of hunting
regulations which strictly regulate bag limits.
Since these regulations were established early in
the twentieth century, the populations of most
ducks have recovered and are now the basis of the
single most popular and economically important
sport hunting in North America.